Electron discharge device with external mode suppression means which separate wanted from unwanted modes and allow for dissipation of unwanted modes



Dec. 6, 1966 G. MOURIER 3,290,545

ELECTRON DISCHARGE DEVICE WITH EXTERNAL MODE SUPP LESSION MEANS WHICHSEPARATE WANTED FROM UNWANTED MODES DISSIPATION OE UNWANTED MODES ANDALLOW FOR 1965 2 Sheets-Sheet 1 Filed March 26,

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30 E ZOmPumJm m0 ZOFUMEQ INV ENTO R G-HOUR/ER ATTORNEY Dec. 6, 1966 G.MOURIER 3,290,545

ELECTRON DISCHARGE DEVICE WITH EXTERNAL MODE SUPPRESSION MEANS WHICHSEPARATE WANTED FROM UNWANTED MODES AND ALLOW FOR DISSIPATION OFUNWANTED MODES Filed March 26, 1965 2 Sheets-Sheet 2 FIGS INVENTORZ G-HOUR/ER BY P g-9 ATTORNEY United States Patent "ice 6 Claims. (c1.315-36) The present invention relates to ultrahigh-frequency amplifiertubes with bi-dimensional delay circuits such as described, for example,in United States Patent No. 2,954,- 505 of September 27, 1960.

In the tubes of this type, in which the interaction between the electronbeam and the ultrahigh-frequency energy to be amplified takes placealong one direction parallel to one of the dimensions of the delaycircuit, while the propagation of the ultra-high-frequency energy takesplace, transversely to the beam, along a direction parallel to the otherdimension of the delay circuit, one encounters certain difiiculties dueto the multiplicity of possible modes of propagation.

There always exists, in effect, one or several modes having phasevelocities and bands of frequencies of propagation near those of theutilized mode, and a danger of auto-oscillation or of operation underunfavorable conditions follows therefrom. This danger is still furtheraggravated by the coupling elements at the output and/ or inputcircuits.

The present invention has for its object a circuit arrangement whichpermits to remedy these difficulties.

According to the present invention, the construction and circuitconnections of an electron tube comprising a bidimensional delaycircuit, means for producing one or several electron beams propagatingin one direction parallel to one of the dimensions of the delay circuit,an input circuit permitting to inject at one of the extremities of thetube ultra-high-frequency waves to be amplified, propagating in adirection parallel to the other dimension of the delay circuit, and anoutput circuit at the opposite extremity of the tube to extract theamplified ultra-highfrequency waves, is characterized by the dispositionof means enabling to produce the sum and the difference of thehalf-waves at least at one of the extremities of the tube, and to causethese sums and differences of waves to pass through distinct paths.

According to a preferred mode of realization of the present invention,the means to produce the sum and the difference of the half-waves areconstituted by so-called magic Ts.

Accordingly, it is an object of the present invention to provide anultra-high-frequency electron discharge device of the type describedhereinabove in which the drawbacks and inconveniences due to thepresence of undesired modes are effectively minimized by simple means.

It is another object of the present invention to provide an arrangementwhich reduces the danger of auto-oscillations or operation underunfavorable conditions in connection with electron discharge tubeshaving a bi-dimensional delay structure.

Still another object of the present invention resides in the provisionof an ultra-high-frequency electron discharge tube producing signalamplification which includes a bi-dimensional wave guiding structure andmeans operable to minimize any interference by undesirable modes withthe mode on which the tube is intended to operate.

These and other objects, features and advantages of the presentinvention will become more obvious from the following description whentaken in connection with the Patented Dec. 6, 1966 accompanying drawingwhich shows, for purposes of illustration only, two embodiments inaccordance with the present invention and wherein:

FIGURE 1 is a schematic perspective view of one circuit arrangementaccording to the present invention for a tube provided with abi-dimensional delay circuit of rectangular form,

FIGURE 2 is a schematic perspective view of a similar circuitarrangement for a tube with a bi-dimensional delay circuit and ofcylindrical structure, and

FIGURE 3 is a perspective view, on an enlarged scale and with partsthereof broken away, of the assembly of FIGURE 2. I

Referring now to the drawing wherein like reference numerals are usedthroughout the various views to designate like parts, and moreparticularly to FIGURE 1. reference numeral 1 designates a conventionalbi-dimensional delay circuit illustrated therein only schematicallywhich may be utilized in an ultrahigh-frequency amplifier tube of highpower. This circuit comprises rows A, A, B, B G, G, H, H, each formed bydistinct delay cells which are schematically shown in the drawing bysquare blocks.

To simplify the drawing, the complete tube has not been illustratedtherein but it sufiices to recall that in such a tube one produces,according to well-known techniques, one or several electron beams,subjected to crossed electric and magnetic fields in such a manner thatthe electrons propagate parallelly to one of the dimensions of the delaycircuit; the ultrahigh-frequency waves to be amplified, which areinjected through an input circuit at one extremity of the tube,propagate along the delay circuit parallelly to the other dimension ofthe delay circuit, and an output circuit, at the opposite extremity ofthe tube, permits to collect the amplified waves.

In the embodiment of FIGURE 1, the direction of propagation of theelectrons is indicated by the arrows 2 and the direction of propagationof the ultra-high-frequency energy on the inside of the tube by thearrow 3.

The input circuit, coupled to the left side of the tube as viewed inFIGURE 1, comprises a magic T 4 of which the branch or section 5 iscoupled, by means of a horn 6, to the cells A, B, C, and D, and thebranch or section 7 is, in a similar manner, coupled to the cells E, F,G, and H by means of a horn 8.

In an analogous manner, the output circuit, coupled to the right side ofthe tube as viewed in FIGURE 1, may comprise a magic T 9 having a branchor section 10 coupled to the cells A, B, C and D by means of a horn 11and a branch or section 12, coupled to the cells E, F, G and H by meansof a horn 13.

When the tube is caused to operate according to the fundamental mode(mode 0), all the cells A to H are in phase at the input of the tube,and in a similar manner, all the cells A to H are in phase at the outputof the tube. The waves collected in that case at the output by the horns11 and 13, combine in the magic T 9 which, by virtue of the well-knownproperties of magic Ts," produces the difference of these waves, that iszero, in the wave guide 14, and the sum, that is all theultra-highfrequency energy available, in the wave guide 15.

However, alongside the utilized fundamental mode appear generally alsodiverse undesirable modes.

If one calls N the number of rows of the cells, this number being 8 inthe case of FIGURE 1, the mode Zrr/N is among the undesirable modes, thenearest to the fundamental mode and generally also the mostobjectionable. However, in the 21r/N mode, the outermost cells A and Hor A and H are out of phase by 211'. Con sequently, there exists betweenthe cells A and H a full wave, presenting a positive phase alongone-half of the cells and a negative phase along the other half.

Under these conditions, one can readily see immediately that the wavesof the mode 27r/ N, that arrive at the magic T 9, appear exclusively inthe wave guide 14 and do not manifest themselves at all in the waveguide 15, which is exactly the reverse of what takes place, as describedhereinabove, for the fundamental mode. It suffices, therefore, toterminate the wave guide 14 by an appropriate impedance to absorbthereat all of the energy of the undesirable mode in question withoutthe possibility that the latter might be reflected toward the interiorof the tube which generally has as its effect to suppress thepossibilities of auto-oscillation on this mode.

The reasoning applied to the output side is equally valid for the inputside .in which the magic T 4 behaves obviously in the same manner as themagic T 9 of the output circuit.

It is to be noted, however, that one may also utilize at the input adifferent circuit from that of the output. Thus, the input circuit maybe a simple wave guide, without any magic T, if the dispositions of theoutput circuit suflice by themselves to eliminate the undesirable mode.

In certain cases, one may also seek to eliminate an undesirable mode atone extremity of the tube and another undesirable mode at the otherextremity thereof. One may, in effect, always find the number of magicTs and of horns necessary for the coupling to the tube to combat thereata given mode of propagation.

FIGURE 2 represents schematically a cylindrical amplifier tube with abi-di-mension delay circuit, connected in accordance with the presentinvention.

The bi-dimensional delay circuits for cylindrical tubes may beassimilated to that of FIGURE 1, wound or rolled upon itself about theaxis of the tube in such a manner that the cells H H come to be adjacentthe cells A A. Such a circuit is, therefore, formed by a number ofrectilinear delay lines, disposed as columns or bars about the axis ofthe tube, and lends itself to be disposed more particularly about anemissive cathode of the magnetron type.

The circuit connection of FIGURE 2 comprises at each extremity of thetube 21 a wave guide 22 and 23, coupled to the tube 21 and connected tothe two arms of the magic T 24 and 25, respectively. Windows 26, 26' and27, 27, which are vacuum-tight and transparent to the electromagneticwaves, are disposed, as indicated :in dash lines, within the wave guides22 and 23, respectively.

FIGURE 3 shows the manner in which the tube 21 is coupled to the guides22 and 23. This figure illustrates, on an enlarged scale, one extremityof the tube 21 with its bi-dimensional delay circuit. The bi-dimensionaldelay circuit is represented schematically by twelve bars or columns 28of which six, longer than the others, emerge into the wave guide towhich they are thus coupled.

With circuits of this type, there exists generally an interest to causethe tubes to operate in the 11' mode, that is, with a phase shiftbetween adjacent columns equal to 1r. If the number of columns k iseven, k=2n, n being an integer, one has 12 full waves along thecircumference of the tube.

However, alongside the 1r mode which one desires to utilize, the circuitmay also become the locus or seat of undesirable modes and particularlyof that in which two adjacent columns are out of phase by which givesrise, along the circumference of the tube, to a number of waves (nl),less by one to that obtained with the 1r mode.

In the given example in which k=l2, the tube operating on the 11' modepresents along its circumference six full waves, and the six columns 28coupled to the wave guides are all in phase. These waves combinetherefore in the magic T which produces the sum thereof in the branch orsection 29 or 30 (FIGURE 2) while no energy appears in the branch orsection 31 or 32 which would represent the differences of waves.

If now the delay circuit becomes also the seat of the undesirable mode51r/6, that is,

with n=6, this mode produces five full waves along the circumference ofthe tube and the six columns 28 are no longer all in phase. Threeconsecutive columns will, therefore, present an opposite phase to thatof three other columns in such a manner that within the magic Ts onewill find substantially all the energy corresponding to the undersiredmode in the branch or section 31 or 32, provided that one chooses forthe magic Ts the optimum orientation which depends on the relativeposition of the nodes of the undesired waves with respect to the columns28.

The magic Ts have been illustrated in FIGURE 2 at the two extremities ofthe tube with a phase shift of between themselves as such an arrangementpermits the elimination of the undesirable waves of two differentorientations. However, depending on the case, it is also possible toorient the two magic TS in the same direction or to utilize only asingle magic T, preferabl at the output side of the tube.

While-I have shown and described two embodiments in accordance with thepresent invention, it is understood that the same is not limited theretobut is susceptible of numerous changes and modifications within thespirit and scope thereof and I, therefore, do not wish to limited to thedetails shown and described herein but intend to cover all such changesand modifications as are encompassed by the scope of the appendedclaims.

I claim:

1. An ultra-high-frequency arrangement comprising:

an electron discharge tube including a two dimensional wave delaystructure, means for propagating at least one electron streamapproximately parallelly to one of the dimensions of said delaystructure, coupling means operatively connected to said wave delaystructure to enable the propagation of electromagnetic waves along saidwave delay structure approximately parallelly to another dimensionthereof and in energy transfer relationship to said electron stream,

and means for producing the sum and the difference of two half-waves atleast within the area of said coupling means and for separating theenergies obtained in said sum and difference, respectively. 2. Anultrahigh-frequency arrangement comprising: an electron discharge tubeincluding a two dimensional wave delay structure, means for propagatingat least one electron stream approximately parallelly to one of thedimensions of said delay structure, coupling means operatively connectedto said wave delay structure to enable the propagation ofelectromagnetic waves along said wave delay structure approximatelyparallelly to another dimension thereof and in energy transferrelationship to said electron stream,

and means for producing the sum and the difference of two half-waves atleast within the area of said coupling means and for separating theenergies obtained in said sum and difference, respectively, includingmagic T means.

3. In an electron discharge tube of the type in which electromagneticwaves propagate substantially parallelly to one dimension of atwodimensional wave-guiding structure in energy exchange relationshipwith at least one electron stream propagating substantially parallellyto the other dimension of said structure, and in which energy of theelectromagnetic waves is adapted to be extracted from said wave-guidingstructure through an output circult,

the improvement essentially consisting of means for producing the sumand the difference of two half- Waves in said output circuit and forseparating the energies in said sum and difference, respectively,

4. In an electron discharge tube effectively having at least one end andof the type in which electromagnetic waves propagate substantiallyparallelly to one dimension of a two dimensional wave-guiding structurein energy exchange relationship with at least one electron beampropagating substantially parallelly to the other dimension of saidstructure,

the improvement essentially consisting of means for producing the sumand the difference of two half waves at said one end of the tube andmeans for separating the energies in said sum and difference,respectively.

5. An ultrahigh-frequency arrangement comprising:

an electron discharge tube effectively having two ends and including atwo dimensional wave delay structure, means for propagating at least oneelectron stream approximately parallelly to one of the dimensions ofsaid delay structure,

output means operatively connected to said wave delay structure near arespective end of the tube to enable the energy transfer ofelectromagnetic waves operable to propagate in said wave delay structureapproximately parallelly to another dimension thereof,

and means for producing the sum and the difference of two half-waves atleast within the area of said tube near said output means and separatingthe energies obtained in said sum and difference, respectively,including magic T means.

6. An ultrahigh-frequency arrangement comprising:

an electron discharge tube effectively having two ends and including atwo dimensional wave delay structure, means .for propagating at leastone electron stream approximately parallelly to one of the dimensions ofsaid delay structure,

input and output means operatively connected to said Wave delaystructure near a respective end of the tube to enable the energytransfer of electromagnetic waves operable to propagate in said wavedelay structure approximately parallelly to another dimension thereof,

and means for producing the sum and the difference of two half-waves atleast within the area of said tube near one of said input and outputmeans and separating the energies obtained in said sum and difference,respectively, including magic T means.

References Cited by the Examiner UNITED STATES PATENTS 2,445,896 7/ 1948Tyrrell 33111 2,849,643 8/ 1958 Mourier 315-514 X 2,954,505 9/1960Mourier 3153.5 X 3,027,521 3/1962 Shelton 33182 HERMAN KARL SAALBACH,Primal Examiner.

R. D. COHN, Assistant Examiner.

1. AN ULTRA-HIGH-FREQUENCY ARRANGEMENT COMPRISING: AN ELECTRON DISCHARGETUBE INCLUDING A TWO DIMENSIONAL WAVE DELAY STRUCTURE, MEANS FORPROPAGATING AT LEAST ONE ELECTRON STREAM APPROXIMATELY PARALLELLY TO ONEOF THE DIMENSIONS OF SAID DELAY STRUCTURE, COUPLING MEANS OPERATIVELYCONNECTED TO SAID WAVE DELAY STRUCTURE TO ENABLE THE PROPAGATION OFELECTROMAGNETIC WAVES ALONG SAID WAVE DELAY STRUCTURE APPROXIMATELYPARALLELLY TO ANOTHER DIMENSION THEREOF AND IN ENERGY TRANSFERRELATIONSHIP TO SAID ELECTRON STREAM, AND MEANS FOR PRODUCING THE SUMAND THE DIFFERENCE OF TWO HALF-WAVES AT LEAST WITHIN THE AREA OF SAIDCOUPLING MEANS AND FOR SEPARATING THE ENERGIES OBTAINED IN SAID SUM ANDDIFFERENCE, RESPECTIVELY.